This present disclosure relates to toners and developers containing the toners for use in forming and developing images, and in particular to toners formed using emulsion aggregation. The disclosure also relates to processes for producing and using such toners and developers.
Emulsion aggregation (EA) toners are used in forming print and/or xerographic images. Emulsion aggregation techniques typically involve the formation of an emulsion latex of the resin particles, which particles have a small size of from, for example, about 5 to about 500 nanometers in diameter, by heating the resin, optionally with solvent if needed, in water, or by making a latex in water using an emulsion polymerization. A colorant dispersion, for example of a pigment dispersed in water, optionally also with additional resin, is separately formed. The colorant dispersion is added to the emulsion latex mixture, and an aggregating agent or complexing agent is then added and/or aggregation otherwise initiated to form aggregated toner particles. The aggregated toner particles are heated to enable coalescence/fusing, thereby achieving aggregated, fused toner particles, United States patents describing emulsion aggregation toners include, for example, U.S. Pat. Nos. 5,370,963, 5,418,108, 5,290,654, 5,278,020, 5,308,734, 5,344,738, 5,403,693, 5,364,729, 5,346,797, 5,348,832, 5,405,728, 5,366,841, 5,496,676, 5,527,658, 5,585,215, 5,650,255, 5,650,256, 5,501,935, 5,723,253, 5,744,520, 5,763,133, 5,766,818, 5,747,215, 5,827,633, 5,853,944, 5,804,349, 5,840,462, and 5,869,215, each of which are incorporated by reference herein in their entirety.
Two main types of emulsion aggregation toners are known. First is an emulsion aggregation process that forms acrylate based, for example, styrene acrylate, toner particles. See, for example, U.S. Pat. No. 6,120,967, the entire disclosure of which is incorporated herein by reference, as one example of such a process. Second is an emulsion aggregation (EA) process that forms polyester, for example, sodio sulfonated polyester, toner particles. See, for example, U.S. Pat. No. 5,916,725, the entire disclosure of which is incorporated herein by reference, as one example of such a process. Alternatively, toner particles can be formed via an EA process that uses preformed polyester latex emulsions made using solvent flash or phase inversion emulsification (PIE) such as those toner methods described in U.S. Patent Application Publication No. 2008/0236446, the entire disclosure of which is incorporated herein by reference. Additionally, so-called ultra low melt polyester toners can be obtained by incorporation of a suitable crystalline polyester. Examples of EA ultra low melt (ULM) polyester toners, include those described in U.S. Pat. Nos. 5,057,392, 5,147,747, 6,383,705, 6,780,557, 6,942,951, 7,056,635 and U.S. Patent Application Pub. No. 2008/0236446, the disclosures of which are incorporated by reference in their entirety.
Emulsion aggregation polyester-based toners have begun to replace styrene-acrylate toners due to the lower achievable minimum fixing temperatures (MFT), wide fusing latitude, good release, high gloss, high blocking temperature, robust particles and suitable triboelectric properties of polyester-based toners. More particularly, lower MFT toners provide the opportunity for higher print productivity and/or reduced fusing temperatures, and therefore lower printer power consumption. However, not all lower MFT toners are suitable to be used in all printing platforms.